replaced os.join with Path objects for cross platform compatability

[powerllama]

Posix paths can be used by nuke in both posix environments (linux, macos), and Windows environments. Using f strings also makes those nodePaste calls a little more readable as well, in my opinion.

There are other places where one could replace the os calls, but they all seem to work just fine in all environments so I left them alone.

[CreativeLyons]

Hey thank you very much, I am going to test this on my end and hopefully Merge it with the main branch. Also, I like the idea of using the f-strings for more clarity on the node pastes . I appreciate it!

[powerllama]

No worries, figured if I was doing it on my end, might as well send it upstream. Without the f-strings, the whole patch could probably just be using pathlib and doing the posix path at the top, but the f-strings called to me.